Yield: 97%

Reaction Conditions:

with trifluoroacetic acid in dichloromethane at 20; for 4 h;

Steps:

2497.B
Step B: Synthesis of cis-(4-amino-cyclohexyl)-carbamic acid benzyl ester. To a solution of cis-(4-tert-butoxycarbonylamino-cyclohexyl)-carbamic acid benzyl ester (6.2 g, 0.018 mol) in 40 mL CH₂Cl₂ was added TFA (2.7 mL, 0.36 mol). The solution was stirred at room temperature for 4 hours. The excess solvent was evaporated off and the resulting oil was dissolved in 30 mL CH₂Cl₂. The organic layer was extracted with 30 mL of a dilute NaOH (aq) / NaHCO₃ (aq) solution. The aqueous layer was back extracted twice with CH₂Cl₂ and the organic layers combined, dried over MgSO₄, and concentrated to yield cis-(4-amino-cyclohexyl)-carbamic acid benzyl ester (4.3 g, 97%) as a colorless oil. The oil was carried forward without further purification. ESI MS m/e 249.2 M + H⁺.

References:

Taisho Pharmaceutical Co. Ltd.;Arena Pharmaceuticals, Inc. EP1464335, 2004, A2 Location in patent:Page/Page column 293